Polymeric wax crystal modifiers for high wax content petroleum oils

ABSTRACT

OIL-SOLUBLE POLYMERS OF UNSATURATED ESTERS HAVING AKYL SIDE CHAINS CONTAINING ABOUT 18 TO 34 CARBON ATOMS IMPROVE FLOW AND POUR POINTS OF HIGH WAX CONTENT PETROLEUM OILS SUCH AS CRUDES, RESIDUA, ETC., AND ARE USEFUL AS DEWAXING ACIDS.

United States Patent 3,729,296 POLYMERIC WAX CRYSTAL MODIFIERS FOR HIGH WAX CONTENT PETROLEUM OILS Harold N. Miller, Plainfield, N.J., assignor to Esso Research and Engineering Company No Drawing. Filed Oct. 14, 1966, Ser. No. 586,654

Int. Cl. C10m 1/26 US. Cl. 44-62 14 Claims ABSTRACT OF THE DISCLOSURE Oil-soluble polymers of unsaturated esters having alkyl side chains containing about 18 to 34 carbon atoms improve flow and pour points of high wax content petroleum oils such as crudes, residua, etc., and are useful as dewaxing aids..

This invention relates to a novel wax crystal modifier composition and to the utilization of same, and more particularly to a wax crystal modifier comprising a polymer prepared from long chain aliphatic esters of unsaturated acids. In another aspect, the invention relates to the utilization of certain long chain ester polymers as blending agents for improving flow characteristics of high wax content petroleum oils, i.e., crudes, residua, and light fuel oils, and especially petroleum oils which boil above 650 F. and have flow points above desired specifications.

It is well known that when petroleum oils are cooled, a turbidity develops which gradually changes into a crystalline precipitate of the wax present in the oil or fuel. As the temperature is lowered, the concentration of solid material increases, developing a gel caused by the formation of a coherent three dimensional network of wax crystals. As a result of this crystal structure, large amounts of oil are entrained in the crystal lattice of wax, thereby preventing its flow. A temperature F. higher than that at which oil ceases to flow (solid point) is referred to as the pour point. The pour points of petroleum oils vary widely, for example, some oils solidify far below zero while others freeze at temperatures up to 80 or 120 F. by virtue of their wax content alone. It is obvious, therefore, that the pour point is critical with regard to the flow characteristics and, consequently, adversely aifects the storage, mixing, pumping, etc. of such oil. Thus, pour point characteristics are significant to the design and/or operation facilities for the storage, heat exchange, pumping, etc. of the oil. Naturally, an oil having a high flow point, e.g., light fuel oils having flow points above 20 F., cnides having flow points above 55 F. and residual fuels having tiow points above about 60 F. would provide a serious problem relative to the design of the facilities mentioned above.

Typical examples of petroleum oils which exemplify the undesirable characteristic of having a flow point above about 65 F. are the residual oils set forth in the following Table I:

F. These oils have represented a particular problem in the past. Particular reference is made to the residuum of a North African crude identified above as Zelten residium which contains about 15-20 Wt. percent wax. This wax content includes waxes of relatively high molecular weight, e.g., from about C and greater, which especially give rise to the above-mentioned problems, i.e., the transporting, storing, etc. of this kind of heavy oil.

While such Zelten residuum typifies the kind of high wax content oils which exemplify undesirable flow properties and the like, such residuum is, in fact, a premium oil as compared to other crude residua which have much lower pour points. This fact may be illustrated by a comparison of Zelten waxy oil with crude petroleum residua known as Aramco and Kuwait, as illustrated in the following Table II:

TABLE II Heavy fuel oil inspections ot' Zelten Aramco Kuwait Target Vol. percent 680 FVT in crude- 35 39 37 Inspections on 680 FVT+z Gravity, API 22 15 14 Sulfur, wt. pereent 0. 4 3.0 4. 2 1 8. 5 Viscosity, SF at 122 110 340 40-175 MNI, wt. percent 2.3 4. 0 3.8 1 7 Conradson carbon, wt.

percent 4. 5 8. 9 10-11 Flow pt.. F 105 65 55 1 Hot filtration sed., wt.

percent 0 01 0. 02 0. 02 1 0. l5

1 Max.

The inspections shown in the foregoing Table II illustrate that the Zelten residuum is a premium product per se, as well as a valuable product for blending and for improving other heavy fuel oils due to its low sulfur content, low viscosity, low MNI (Modified Naphtha Insolubles), and low Conradson Carbon number. Furthermore, it is low in ash and vanadium content. These qualities also make Zelten crude an excellent source of cracking stock for obtaining various valuable products, such as straight chain olefins, and the like.

As presented, the column headed by the notation Target indicates the parameters of blends which are desirable using said Zelten residuum as a blending stock, i.e., providing the flow point can be suitably lowered. For example, it may be desirable to mix the Zelten residuum in a 50/50 mixture with the Aramco or Kuwait residuum. While such blending lowers the wax content, the flow point is generally not sutficiently reduced so as to significantly change the characteristics of the resulting mixture. Thus, while it is found that blending of the extremely high wax content petroleum residual oils with other blending stocks may lower the wax content, the flow point cannot be satisfactorily reduced without using the polymeric additives of this invention to lower the flow point below the 75 F. target referred to above in Table I. For example, in the 50/50 Zelten/Aramco blend, the ad- TABLE I.PETROLEUM RESIDUAL OILS Location Libya Nigeria Venezuela Sumatra Field- Zelton Mabruk Raguba Dahra Waha Bomu Ebubu Oloibiri San Joaquin Minas Flow points of residual F.) 97 95/100 85 100+ 100+ 100+ 100+ FVT cut point of residual 680+ 680+ 650+ 650+ 650 650 650 660 650 650 It should be noted that the present invention is directed to a wide range of petroleum oils, but special reference is made to high pour point oils, e.g., residual oils boiling above 650 F. and having a flow point above dition of only 0.05 wt. percent of the additive of the instant invention has been found suflicient to meet the target of 75 F. flow point. This advantageous aspect will be discussed more fully hereinlater.

As mentioned above, because of the ability of high pour point, e.g., high wax content oils to resist the free flow at lower temperatures, their use at these conditions is very limited. Conventional dewaxing operations to reduce the pour point are not always feasible nor satisfactory, and they'are usually expensive. For this reason additives capable of lowering the pour point of oils and distillates thereof are successfully applied to extend their use at lower temperatures. A vast number of various substances have been claimed as pour depressants, primarily for use in lubricating oils, however, these materials are usually found to be ineffective in high wax content residual oils.

Furthermore, although high pour point petroleum oils or mixtures containing such petroleum oils may have a relatively low viscosity as measured by conventional methods as compared to heavy oils of low wax content, the handling of the high wax content oils creates special difliculties which are due to the manner in which the oil undergoes changes in flow characteristics on being subjected to changes in temperature. Generally, the standard ASTM pour point is reasonably indicative of how low the temperature of an oil can be decreased and at what point it can be satisfactorily made to flow. However, with high wax content oils, such as the above-described Zelten residual oil, the flow point determined by standardized procedure is variable and is further, a func-v tion of prior thermal treatment. This phenomena may be referred to as a pour gap and is determined when highly waxy residua in the presence of natural pour depressants or certain synthetic pour depressants exhibit pour reversion. This is determined by subjecting a mixture of residuum and pour depressant through a series of heating and reheating cycles so as to determine a series of pour points at various reheat temperatures. The following Table III illustrates the effects of various known additives on the pour points at various reheat temperatures, and, consequently, the flow point of Zelten residuum.

4 can be 'kept fluid in storage, for pumping, transporting, and the like.

It is accordingly, an object of the present invention to provide an additive which substantially improves the flow characteristics of wax-containing petroleum oils.

It is also an object of the present invention to provide an additive which effectively serves to improve the flow characteristics of extremely high wax content petroleum oils such as crudes, residua and light fuel oils that have pour or flow points above 20 F.

It is a special object of the present invention to provide superior blending agents for improving the flow characteristics of extremely high wax content petroleum residual oils that boil above 650 F. and have pour or flow points above desired specifications.

It is a still further object to provide a new and highly improved class of additive materials which modify the size and shape of the wax crystals contained within the above petroleum oils in such a manner as to permit more rapid separation of the wax in a dewaxing process.

Other objects and advantages will become apparent to one skilled in the art upon a further reading of the following description.

Accordingly, the present invention is directed to a petroleum oil composition comprising a high wax content petroleum oil, e.g. an oil having a flow point or pour point above 20 F. and especially a residual oil having a boiling point above about 650 F. and a flow point above about 75 F., improved with respect to its wax crystal characteristics by having incorporated therewith an amount of about 0.005 to about 5.5 wt. percent of a polymer prepared by the polymerization of certain long chain esters. The present invention especially contemplates the copolymerization of long chain unsaturated esters with an additional ester such as a vinyl ester of a short chain fatty acid. Although the mechanism by which the polymers and copolymers act to impart their surprising potencies is not fully understood, it has been found TABLE III.-EFFECTS OF ADDITIVES ON FLOW POINTS OF 680 F.+ VIRGIN ZELTEN RESIDUUM Tan of Avg. of

N o. of Flow Pour Additive Cone. 100 F. 115 F. 130 F. 150 F. 180 F. 200 F. tests point 1 gap 680 F.+ Virgin Zelten Residuum- 100 100 105 105 105 100 95 (3) 105 10 Wax-phenol (ex 180 mp wax) 0. 30 90 97 102 110 85 60 (2) 110 Wax-naphthalene (ex 180 mp wax) 0.30 83 99 109 103 100 65 (4) 109 44 Wax-naphthalene (ex 150 mp wax) 0.30 98 105 105 105 109 90 (4) 109 19 Target pour points 75 75 75 76 76 75 75 1 Flow point-maximum pour point obtained after a series of pour point determinations at a series of reheat temperatures. (TRH).

It is apparent from the foregoing table that conventional pour depressants fail to suitably reduce the flow point of the residuum inasmuch as reheating through one or more temperature cycles results in at least one pour point which would be essentially inoperable for commercial handling of the residuum. Thus, the necessity for a suitable additive which will effectively reduce the flow point of highly waxy residua through any number of reheat cycles is readily apparent.

In addition, from the foregoing Table III it is apparent that a necessity exists for modifying the standard A'STM pour point procedure so as to obtain a reproducible and more meaningful measure of flow characteristics and to efliciently test the high wax content residual oils. Accordingly, in the tests illustrated in Table III, a sample of oil is first heated to 200 F. and is subsequently cooled to 32 F. 'before it is again heated to an intermediate temperature in the range of 90 to 200 F. for testing under the standard ASTM procedure. By putting the oil through a temperature cycle series, such as mentioned above, a determination is made of the pour gap as well as the flow point corresponding to the maximum pour point in the series. Such flow point is the optimum meas are achieved as yet for determining how well such oil or mixtures thereof wherein R is a higher alkyl group the polymethacrylates which contain two or more recurring units:

and the fumarate or maleate-vinyl acetate copolymers which contain one or more units such as:

(v1) OR -CH H on -CH-- /x 2 3 1. 41:0

wherein in each of Formulas IV, V, and VI, R has a total chain length of from about 18 to about 34 carbon atoms, excluding branching therein, and x and y are as defined above. Moreover, the long chain ester monomers described above may be copolymerized with various amounts, e.g. 0-60 mole percent, of short chain esters such as methacrylates, acrylates, fumarates, maleates and the like, wherein the alcoholic residue contains from 1 to about 13 carbon atoms.

The long chain aliphatic esters of unsaturated dibasic basic acids, i.e., the acrylic acids, which are employed as monomeric components in producing the additive agents employed in accordance with the invention are esters of C to about C especially the C -C unsaturated monobasic acids. Examples of acids which may be esterified to produce such esters include acrylic acid, the butenic acids, such as crotonic, isocrotonic, vinylacetic and methacrylic acid, the pentenic acids such as, teglic, angelic, and senecioic acid, the hexenic acids, etc. Esters of acrylic acid, methacrylic acid and the butenic acids are preferred for the purposes of this invention.

The long chain aliphatic esters of unasturated dibasic acids which are employed as monomeric components in producing the additive agents employed in accordance with the invention are esters of C -C unsaturated dibasic acids. Examples of acids which may be esterified to produce such esters include maleic acid, fumaric acid, citraconic acid, mesaconic acid, glutaconic acid, itaconic acid and the like. Esters of the butenedioic acids, fumaric acid and maleic acid and mixtures of the two, are preferred for the purposes of this invention.

The short chain vinyl esters used as monomers in preparing the copolymers of this invention are vinyl esters of low molecular weight acids containing from about 2 to about 6 carbon atoms per molecule. Specific examples of such vinyl esters include vinyl acetate, vinyl propionate, vinyl butyrate, vinyl pivalate, vinyl pentanoate, vinyl hexanoate and vinyl benzoate, the like and mixtures thereof.

Examples of long chain vinyl esters used in preparing the polymers of this invention include, among others, vinyl nonadecanoate, vinyl arachidate, vinyl behenate, vinyl 6 tetracosanoate, vinyl hexacosanoate, vinyl tricontanoate, the like and mixtures thereof.

The long chain aliphatic esters described above may be prepared from aliphatic alcohols containing from about 18 to about 34 carbon atoms per molecule. Saturated aliphatic alcohols containing from about 19 to 29 carbon atoms per molecule are preferred for use in preparing the esters. Saturated straight chain alcohols of from 19 to 27 carbon atoms per molecule are particularly effective for purposes of the invention. Mixed esters derived by the reaction of the acids with a mixture of alcohols may be used. Examples of alcohols suitable for use in producing the esters include straight chain primary alcohols such as stearyl, nonadecyl, eicosyl, heneicosyl, docosyl, tricosyl, tetracosyl, pentacosyl, hexacosyl, heptacosyl, octacosyl, noncosyl, triacontyl alcohols and the like; branched alcohols, e.g. oxo alcohols such as 2-methyl stearyl, Z-methyl eicosyl, Z-methyl docosyl and the like.

Commercially marketed mixtures of alcohols consisting essentially of saturated alcohols of the requisite chain length may be employed in preparing the long chain esters. One such mixture is a hydrogenated fish oil fraction and is marketed under the trade name Behenyl. This mixture of alcohols consists primarily of docosyl alcohol but contains minor amounts of other alcohols containing from 16 to 24 carbon atoms per molecule.

The dibasic acid esters of this invention may be prepared from straight chain as well as branched chain alcohols having a chain length, excluding branching, of from 18 to 34 carbon atoms per molecule. Typical examples of long chain esters of unsaturated dibasic acids useful in preparing the polymer and copolymer additives include eicosyl fumarate, docosyl fumarate, eicosyl maleate, docosyl citroconate, decosyl maleate, eicosyl mesaconate, eicosyl citraconate, decosyl itaconate, tricosyl fumarate, tetracosyl maleate, pentacosyl citraconate, hexacosyl mesaconate, heptacosyl itaconate, octacosyl fumarate, noncosyl maleate, triacontyl citraconate, hentriacontyl mesaconate, dotriacontyl itaconate, triacontyl fumarate, the like and mixtures thereof.

The monomers described in the preceding paragraphs are polymerized in a conventional manner to produce the polymers useful in the present invention. For example, the polymerization reaction may be carried out without diluent or in a solution of a hydrocarbon solvent such as heptane, benzene, cyclohexane or white oil at a temperature in the range of from about 60 F. to about 250 F. and may be promoted by gamma radiation or by means of a peroxide type catalyst such as benzoyl peroxide, a hydroperoxide or an azo catalyst such as alpha-alphaazo-bis-isobutyronitrile. It is generally preferred to carry out the polymerization reaction under a blanket of an inert gas such as nitrogen or carbon dioxide in order to exclude oxygen. The polymerization time may vary from about 1 to about 36 hours.

The polymers of this invention may have a viscosity average molecular weight in the range of from about 1400 to about 100,000 or higher, i.e. the upper range is limited only by the polymer oil solubility. It is preferred, however, that the molecular weight be within the range between about 1800 to about 30,000.

The amount of short chain vinyl ester (i.e., those esters wherein the side chain R contains from 1 to about 5 carbon atoms) present in the copolymers of this invention as compared to the amount of long chain esters (i.e., those e'sters wherein the side chain R contains from about 18 to about 34 carbon atoms) present is in the range from about 10 to about mole percent, the preferred range being from about 25 to 75 mole percent. Inasmuch as the ester linkage, polymer backbone and requisite side chain length are related to the polymer activity, the long chain monomers of this invention may be polymerized together in any portion desired (i.e., 0-100 mole percent) to secure the maximum potency in a given base stock.

The final additive polymers of this invention may be blended directly with the high wax content petroleum oils. Polymer concentrations within the range of from 0.0025 to 5.0 wt. percent based on weight of wax-containing oil will be operable and will give the desired improvement in flow characteristics. Based on economic as well as flow modifying reasons, from about 0.003 to 0.45 wt. percent of the additive is preferably employed.

The additives of this invention are found compatible with other additive materials and may, if desired, be blended with petroleum oils containing minor amounts of viscosity index improvers, rust inhibitors, oiliness agents, oxidation inhibitors and the like.

The additives of this invention also exhibit utility as a dewaxing aid. For example, admixtures of the polymers of this invention with a wax-containing oil may be processed by chilling the admixture in any suitable manner to a wax precipitation temperature, e.g., from about 30 to about -+20 F. The precipitated wax may then be removed by centrifugation or filtration, preferably the latter. Particularly desirable results are obtained in the conventional solvent dewaxing process wherein the oil, dewaxing aid and dewaxing solvent are admixed at elevated temperatures to form a solution which may then be d'ewaxed in the manner set forth above. In general, it has been found that solvent dewaxing feeds comprising the hereinbefore specified amount of polymer, from about 50 to about 90 wt. percent of the dewaxing solvent and from about 10 to about 50 Wt. percent of the wax-containing oil can be easily and efficiently filtered in conventional dewaxing filtration equipment. Nonlimiting examples of suitable solvents include benzene, toluene, acetone, methylethyl ketone, propane, hexane, ethylene dichloride, aliphatic alcohols, naphtha and mixtures thereof.

The superior additives of the present invention may be understood more fully from the following examples illu'strating same.

EXAMPLE 1 Preparation of behenyl fumarate Two hundred grams of behenyl alcohol, 38 grams fumaric acid, 500 ml. n-heptane and 5 grams p-toluenesulfonic acid were heated to reflux and the water evolved was collected in a Dean-Stark trap. At the end of a 6 hour period, 11 mls. of water were collected and the reaction completed. The solution was cooled to 50 C. and washed with 2-100 ml. portions of sodium carbonate and then with 150 ml. portions of water until a pH of 7 was reached. The heptane solution was then dried over magnesium sulfate, filtered and the solvent removed under reduced pressure. The yield was 95%.

One hundred grams of the thus produced behenyl fumarate and 150 ml. n-heptane were charged to a one liter polymer kettle, heated to 60 C. and sparged with nitrogen for a 15 minute period. A solution of 0.8 gram t-butyl perbenzoate in 30 grams vinyl acetate (sparged with nitrogen) was then added to the fumarate ester solution and reaction mixture heated to 8590 C. After a period of 9 hours, the fumarate ester was completely converted to polymer, and a 90% yield of behenyl fumaratevinyl acetate copolymer was obtained. The number average molecular weight as determined by osmometry Was 20,000.

EXAMPLE 2 Preparation of n-C methacrylate ester To a solution of 88 grams of n-C alcohol tetracosanol), 150 ml. heptane, 3 grams p-toluenesulfonic acid and 1 gram hydroquinone, heated to 80 C., were added 22 grams methacrylic acid over a 1 hour period. The reaction mixture was refluxed for 3 hours and 4.5 ml. of water Was collected in a Dean-Stark trap during this period. The solution was then cooled to 50 C. and

Washed with 100 ml. water, 2X 100 ml. of 20% sodium carbonate, 2% sodium hydroxide solution and finally with 100 ml. portions of water until pH 7 is reached. The heptane solution was then dried over magnesium sulfate, filtered and the solvent removed under reduced pressure. The yield was A gram sample of the resulting n-C methacrylate ester dissolved in 100 ml. n-heptane was sparged with nitrogen for a 15 minute period. A 200 mg. portion of VAZO catalyst (azobisisobutyronitrile) was added and the solution was heated to a temperature of 75 C. and held at this temperature for a total of 6-8 hours. Thickening of the solution was noted after a 2 hour period. The reaction mixture was finally filtered and the solvent removed under reduced pressure. The yield of dialyzed polymer was about 90% with a number average molecular wieght of 41,000.

EXAMPLE 3 Two copolymer additives were added to a virgin Zelten residuum in various concentrations. Both lower and upper pour point thermal cycles were applied to the residuum per se and to samples of the residuum containing said various amounts of copolymeric additives. The resulting data are tabulated in Table IV wherein the amounts of copolymeric additive containing equal molar proportions of the monomers, the temperatures in the thermal cycles, and the resulting pour points are set forth.

X Lower pour point thermal cycle: 200 F. 32 F. 200 F. Lower l'gg e i pour point thermal cycle: 200 F. 32 F. F. Upperpour point.

From the foregoing data it can be seen that certain copolymers prepared from alkyl fumarates and vinyl esters improve the flow characteristics of high wax content residuum by effectively depressing the pour point of same. As will be apparent from an examination of the comparative data reported in Table IV, the long chain ester monomers of this invention must contain a side chain having a minimum carbon content of 18 atoms.

EXAMPLE 4 The following example illustrates the use of a docosanoyl fumarate-vinyl acetate copolymer which has been dialyzed.

In an embodiment of the present invention, the polymerization reaction products may, if desired, be subsequently subjected to dialysis. As employed herein, the term dialysis relates to the preferential diffusion of one or more lower molecular weight components of a solution of polymers in a specific solvent through a semipermeable membrane in the direction of a liquid-phase consisting predominantly of solvent. In general, higher molecular weight components are found to diffuse very slowly or not at all while lower molecular weight components in true solution diffuse rapidly. It has been found from dialysis experiments that the active pour depressant components of suitable molecular weight will not diffuse through a thin rubber membrane while the importent, e.g., diluent oil, etc., diffuse quite rapidly through said membrane. It is found, advantageously, that such dialysis can be effected at temperatures ranging from about 20 to about 150 C. and preferably about 30 to C.

Accordingly, a quantity of a docosanoyl fumaratevinyl acetate copolymer was dissolved in hexane solvent 9 and dialyzed at reflux temperature for 10 hours through a thin rubber membrane against pure hexane solvent. Recovery of product which had not dialyzed, after removal of the hexane solvent under reduced pressure, yielded a viscid material which had a molecular weight of about 22,500. The thus prepared additive was employed in a 1 0 EXAMPLE 7 In order to illustrate the criticality of ester linkage as well as chain length, the following polymers were tested in Brega residual fuel and were found to have little or no activity in spite of their possessing the optimum side chain length. The resulting data is presented in Table VIII.

TABLE VIII Pour point at reheat temp. (T88), of-

Polymer, 0.3 wt. percent M01. wt. 200 F. 180 F. 150 F. 130 F. 115 F. 100 F.

Polymer of Ca1+ a-olefin (C22 and higher side chains) 2, 828 75 110 105 105 75 110 Polymer of 022-23 a-olefin (CED-2551116 chains) 2,598 105 110 110 110 100 110 Untreated Zelten Residuum 105 105 105 105 105 105 EXAMPLE 8 647+ FVT Brega residuum. The effect of the additive in depressing pour point of the residuum is illustrated in Table V wherein 0.15 wt. percent of the additive is added to said residuum.

The flow improving characteristics of a polymer additive of this invention were also evaluated in a Gel Test TABLE V Wt. per; Pour point at reheat temp. (Tan). ofcent Additive cone. 200 F. 180 F. 150 F. 130 F. 115 F. 100 F.

647+ FVT Zelten 105 110 105 105 105 105 C22 vinyl acetate-iumarate copolymer 2 0. 55 70 75 75 75 70 Target 75 75 75 75 75 75 1 Additive concentration in 647+ FVT Zelten residuum.

2 Copolymer is a dialysis fraction residue and amounts to about 90% of the crude polymer:

EXAMPLE 5 In a manner similar to the preceding examples, a plurality of polymeric and copolymeric additives within the scope of the present invention were evaluated as flow improvcrs in Brega residuum. From the data presented in Table VI, it is evident that these additives evidence a beneficial effect on the residuum.

TABLE VI.EVALUATION OF EXPERIMENTAL POLYMERS AS FLOW IMPROVERS IN BREGA RESIDUUM Modified flow test results, pour points at reheat temp.,

Percent additive mol. wt. 200 F. 180 F. 150 F. 130 F. 115 F. 100 F.

Untreated residuum. 105 110 105 105 105 105 0.15 Oz; iumarate-vinyl acetate copolymer 1 70 75 75 75 70 0.15 On polymethaerylat 75 85 95 95 85 85 0.15 Czo-Czz polymethaerylate 30, 000 80 85 105 85 80 75 0.15 behenyl fumaratevinyl acetate copolymer 65 70 90 70 55 55 0.15 Oz; fumarate-vinyl acetate copolymer 75 80 95 90 0.15 Oz; polymethacrylate 3 41, 000 65 70 90 95 0.15 022-024 polymethacrylate. 24, 015 70 70 70 75 80 0.15 behenyl polyacrylate 52, 600 50 60 65 45 45 1 Polymer of Example 3.

2 Polymer of Example 1.

3 Dialyzed polymer of Example 2.

EXAMPLE 6 mum pressure required to move the gelled crude 011. The

Three additive compositions (defined above) of the present invention were added to a heavy crude oil in order to illustrate their pour depressant activity. In each instance, 0.075% additive was added and the resulting pour point is compared with the similar base blend but with no additive. The data is presented in Table VII.

TABLE VII Pour depressant activity of experimental polymers in heavy crude oil Percent aditive Pour point, F.

Base blend no additive 75 0.075 behenyl fumarate-vinyl acetate copolymer 35 0.075 C fumarate-vinyl acetate copolymer 20 0.075 C -C polymethacrylate 45 Crude oil consisting of 50/50 vol. mixture of Redwash crude from Utah and Rungely crude from Western Colorado.

results were as follows:

1 Pipe wall temperature after cooling within range between about 33 and 41 F.

2 Crude oil consisting of 50/50 vol. mixture of Redwash crude from Utah and Rangely crude from western Colorado.

8 Molecular weight of about 19.000.

From the foregoing it can be concluded that the polymers of the instant invention very effectively improve the pumpability of high wax content crude oils.

EXAMPLE 9 This example serves to illustrate the dewaxing aid characteristics of the polymers of the present invention.

A wax-containing oil having the properties shown below 75 in Table X was dewaxed in the following manner: the

test oil was diluted at 140 -F. with a solvent consisting of 57 wt. percent methylethyl ketone and 43 wt. percent toluene at a solvent/oil ratio of 3.5/1 and then chilled at the rate of 3 F. per minute from a feed temperature of 140 F. to a filter temperature of -10 F. The chilled mixture was then continuously filtered through a refrigerated circular leaf filter at a pressure diiferential of 25 inches of mercury. The filtration cycle consisted of a filtration time of 33 seconds, a drying time of 10 seconds, a wash time of 22 seconds, and a second drying time of 17 seconds.

TABLE X Properties of test oil 1 Inspection:

ASTM viscosity at 210 F., SUS' 135 Boiling point range, F 400-900 ASTM gravity 60/ 60 F., API 27.1 ASTM pour point, F. 145 Wax content, wt. percent 12 Baton Rouge Bright Stock from East Mississippi Crude.

TABLE XI Dewaxing a Baton Rouge Bright Stock 1 Filtration rate,

Dewaxing aid used, 0.06 wt. percent GaL/hr. ft. None 4.7 n-C polymethacrylate 11.7 n-C fumarate-vinyl acetate copolymer 18.8 Behenyl fumarate-vinyl acetate copolymer 17.0

Test oil of Table IX.

-It is not intended that this invention be limited to the specific examples presented by way of illustration. The scope of the invention is limited only by the appended claims.

What is claimed is:

1. An oil composition having improved flow or pour point characteristics which comprises wax-containing oil selected from the group consisting of residua boiling above about 650 F. and crude oil, having incorporated therewith a wax modifying effective amount of oil-soluble flow improving polymer having molecular weight of at least 1400 selected from the group consisting of:

(a) polymers consisting essentially of long chain unsaturated ester selected from the group consisting of -(1) esters of C to C saturated aliphatic alcohol having a substantially linear C to C alkyl group and unsaturated carboxylic acid selected from the group consisting of C to C monobasic acid and C to C dibasic acid and (2) vinyl esters having a substantially linear C to C alkyl group attached to the carbonyl group of said vinyl ester, and mixtures thereof;

-(b) copolymers consisting essentially of said long chain unsaturated ester and about to about 90 mole percent of short chain unsaturated vinyl ester having 1 to 5 carbons in a side chain; and

(c) copolymers consisting essentially of said long chain unsaturated ester and between 0 to about 60 mole percent of a short chain ester selected from the group consisting of methacrylates, acrylates, fumarates, and maleates, wherein the alcoholic residue of such short chain esters contains 1 to 13 carbon atoms.

2. A composition according to claim 1, wherein said oil is residua having a pour point above 65 F.

3. A composition according to claim 1, wherein said oil is crude oil having a pour point above about 40 F.

4. A composition according to claim 1 wherein said long chain unsaturated ester is acrylate ester.

5. A composition according to claim 1, wherein said long chain unsaturated ester is methacrylate ester.

6. A composition according to claim 1 wherein said long chain unsaturated ester is fumarate ester.

7. A composition according to claim 1 wherein said molecular weight is in the range of about 1400 to 100,000 and wherein the amount of said polymer in said oil is about .0025 to 5 weight percent.

8. A composition according to claim 1, wherein said saturated aliphatic alcohol of (a) contains about 19 to 27 carbon atoms, and said molecular weight is about 1800 to 30,000.

9. A composition according to claim 1, wherein said flow improving polymer is a homopolymer of C methacrylate.

10. A composition according to claim 1, wherein said flow improving polymer is a copolymer of C fumarate and vinylacetate.

11. A composition according to claim 1, wherein said fiow improving polymer is a copolymer of C and C methacrylate.

12. A composition according to claim 1, wherein said flow improving polymer is a homopolymer of C polymethacrylate.

13. A composition according to claim 1, wherein said flow improving polymer is a polymer of behenyl polyacrylate.

14. A composition having improved flow or pour point characteristics which comprises a Wax-containing residue from the topping of crude oil and boiling above 650 F. having incorporated therewith a wax modifying effective amount of oil soluble flow improving polymer having a molecular weight of at least 1400 selected from the group consisting of (a) polymers consisting essentially of long chain unsaturated esters selected from the group consisting of 1) esters of unbranched C to C saturated aliphatic alcohols and unsaturated carboxylic acids selected from the group consisting of C and C monobasic acids and C dibasic acids and (2) vinyl esters having an unbranched C to C alkyl group attached to the carbonyl group of said vinyl ester; (b) copolymers consisting essentially of said long chain unsaturated ester and a short chain unsaturated vinyl ester; and

(c) copolymers consisting essentially of said long chain unsaturated ester and a short chain ester selected from the group consisting of methacrylates, acrylates, fumarates and maleates.

References Cited UNITED STATES PATENTS 2,204,967 1/ 1940 Moser 2528.55 X 2,322,012 6/ 1943 Frolich 25259 X 2,352,213 6/ 1944 Lieber et al. 25259 2,628,198 2/ 1953 Arundale et al. 25256 2,825,717 3/1958 Cashman .5 25256 X 3,222,282 12/ 1965 Berkowitz et a1. 25256- X 3,238,133 3/1966 Lorensen 25256 3,239,445 3/1966 Leonard et al 20833 3,248,186 4/1966 Brownawell et al 44-62 DANIEL E. WYMAN; Primary Examiner W. H. CANNON, Assistant Examiner US. 01. X.R. 

